Restore from a previous full backup's tarfile

Usage:  adb restore [tarfilename]

Restores app data [and installs the apps if necessary from the backup
file] captured in a previous invocation of 'adb backup'.  The user
must explicitly acknowledge the action on-device before it is allowed
to proceed; this prevents any "invisible" pushes of content from the
host to the device.

Known issues:

* The settings databases and wallpaper are saved/restored, but lots
  of other system state is not yet captured in the full backup.  This
  means that for practical purposes this is usable for 3rd party
  apps at present but not for full-system cloning/imaging.

Change-Id: I0c748b645845e7c9178e30bf142857861a64efd3

1 files changed, 65 insertions, 7 deletions

diff --git a/services/java/com/android/server/SystemBackupAgent.java b/services/java/com/android/server/SystemBackupAgent.java
index 54555bb..99c8af6 100644
--- a/services/java/com/android/server/SystemBackupAgent.java
+++ b/services/java/com/android/server/SystemBackupAgent.java
@@ -37,16 +37,25 @@ import java.io.IOException;
 public class SystemBackupAgent extends BackupAgentHelper {
     private static final String TAG = "SystemBackupAgent";
 
-    // These paths must match what the WallpaperManagerService uses
+    // These paths must match what the WallpaperManagerService uses.  The leaf *_FILENAME
+    // are also used in the full-backup file format, so must not change unless steps are
+    // taken to support the legacy backed-up datasets.
+    private static final String WALLPAPER_IMAGE_FILENAME = "wallpaper";
+    private static final String WALLPAPER_INFO_FILENAME = "wallpaper_info.xml";
+
     private static final String WALLPAPER_IMAGE_DIR = "/data/data/com.android.settings/files";
-    private static final String WALLPAPER_IMAGE = WALLPAPER_IMAGE_DIR + "/wallpaper";
+    private static final String WALLPAPER_IMAGE = WALLPAPER_IMAGE_DIR + "/" + WALLPAPER_IMAGE_FILENAME;
+
     private static final String WALLPAPER_INFO_DIR = "/data/system";
-    private static final String WALLPAPER_INFO = WALLPAPER_INFO_DIR + "/wallpaper_info.xml";
+    private static final String WALLPAPER_INFO = WALLPAPER_INFO_DIR + "/" +  WALLPAPER_INFO_FILENAME;
+
 
     @Override
     public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
             ParcelFileDescriptor newState) throws IOException {
         if (oldState == null) {
+            // Ah, it's a full backup dataset, being restored piecemeal.  Just
+            // pop over to the full restore handling and we're done.
             runFullBackup(data);
             return;
         }
@@ -66,11 +75,18 @@ public class SystemBackupAgent extends BackupAgentHelper {
     }
 
     private void runFullBackup(BackupDataOutput output) {
-        // Back up the data files directly
-        FullBackup.backupToTar(getPackageName(), null, null,
-                WALLPAPER_IMAGE_DIR, WALLPAPER_IMAGE, output);
-        FullBackup.backupToTar(getPackageName(), null, null,
+        fullWallpaperBackup(output);
+    }
+
+    private void fullWallpaperBackup(BackupDataOutput output) {
+        // Back up the data files directly.  We do them in this specific order --
+        // info file followed by image -- because then we need take no special
+        // steps during restore; the restore will happen properly when the individual
+        // files are restored piecemeal.
+        FullBackup.backupToTar(getPackageName(), FullBackup.ROOT_TREE_TOKEN, null,
                 WALLPAPER_INFO_DIR, WALLPAPER_INFO, output);
+        FullBackup.backupToTar(getPackageName(), FullBackup.ROOT_TREE_TOKEN, null,
+                WALLPAPER_IMAGE_DIR, WALLPAPER_IMAGE, output);
     }
 
     @Override
@@ -96,4 +112,46 @@ public class SystemBackupAgent extends BackupAgentHelper {
             (new File(WALLPAPER_INFO)).delete();
         }
     }
+
+    @Override
+    public void onRestoreFile(ParcelFileDescriptor data, long size,
+            int type, String domain, String path, long mode, long mtime)
+            throws IOException {
+        Slog.i(TAG, "Restoring file domain=" + domain + " path=" + path);
+
+        // Bits to indicate postprocessing we may need to perform
+        boolean restoredWallpaper = false;
+
+        File outFile = null;
+        // Various domain+files we understand a priori
+        if (domain.equals(FullBackup.ROOT_TREE_TOKEN)) {
+            if (path.equals(WALLPAPER_INFO_FILENAME)) {
+                outFile = new File(WALLPAPER_INFO);
+                restoredWallpaper = true;
+            } else if (path.equals(WALLPAPER_IMAGE_FILENAME)) {
+                outFile = new File(WALLPAPER_IMAGE);
+                restoredWallpaper = true;
+            }
+        }
+
+        try {
+            if (outFile == null) {
+                Slog.w(TAG, "Skipping unrecognized system file: [ " + domain + " : " + path + " ]");
+            }
+            FullBackup.restoreToFile(data, size, type, mode, mtime, outFile);
+
+            if (restoredWallpaper) {
+                WallpaperManagerService wallpaper =
+                        (WallpaperManagerService)ServiceManager.getService(
+                        Context.WALLPAPER_SERVICE);
+                wallpaper.settingsRestored();
+            }
+        } catch (IOException e) {
+            if (restoredWallpaper) {
+                // Make sure we wind up in a good state
+                (new File(WALLPAPER_IMAGE)).delete();
+                (new File(WALLPAPER_INFO)).delete();
+            }
+        }
+    }
 }